Pen



FIG. 1 is a top isometric view of a pen in accordance with the new design;

FIG. 2 is a left side elevation view thereof, a right side elevation view being a mirror image thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a rear isometric view thereof; and,

FIG. 6 is a front isometric view thereof.

The broken lines shown in FIG. 6 illustrate portions of the pen that form no part of the claimed design. 

CLAIM The ornamental design for a pen, as shown and described. 